The invention relates to a high pressure rotary pump in a pot housing with a pressure cap as well as to a use of this pump.
The pot housing pump is usually a multi-stage rotary pump in which the impellers are arranged in-line or back-to-back on the shaft. High pressures can be produced with this pump. As a rule, a drive unit is coupled to the shaft at the low pressure side. At the opposite side, the housing is terminated by the pressure cap. The pressure cap has a flange part with which sealing takes place against the internal pressure, i.e. against the pressure of a pumped liquid. A pot housing pump of the back-to-back type is known from EP-B-0 248 104, which includes two multi-stage rotary pumps arranged at a common shaft.
In a further development of this known pot housing pump, the pressure cap and the flange part provided for the sealing form a unit, with the flange simultaneously serving as a fastening means. It is fastened to the end face of the housing by means of a plurality of expansion bolts. An annular groove into which an O-ring is placed as a seal is let into a sealing surface of the housing. The pressure of the pumped fluid brings about a load on the pressure cap due to which the sealing flange area can raise so far that a leak occurs. An attempt has been made to remedy this defect in that the sealing surface is reduced to a narrow annular zone at the base of the flange and a contact between the flange and the sealing surface of the housing outside the annular zone is eliminated by cutting back the flange surface. The pressure intensity in the sealing region was thereby increased; however, without achieving the desired effect of a leak-free seal.